Traffic intersection



y 1957 D. 'c. GAZIS ETAL 3,323,106 TRAFFIC INTERSECTION Filed April 29, 1954 1o SheCs-Sheet 1 CONTROL CIRCUIT INVENTORS DENOS C. GAZIS R E NFREY B. POTTS ATTORNEY y 1967 D. c. GAZIS ETAL TRAFFIC INTERSECTION 10 Sheets-Sheet 2 Filed April 29, 1964 y 0, 1967 D. c. GAZlS ETAL 3,323,106

TRAFFIC INTERSECTION Filed April 29, 1964 1O Sheets-Sheet 3 TRAFFIC LI GHT 22b COMMON RETURN CONSTANT SUPPLY I & 11

TRAFFIC LIGHT 22c y 1967 D. c. GAZIS ETAL 3,323,106

TRAFFIC INTERSECTION Filed April 29, 1964 10 Shets-Sheet 4 TRAFFIC LIGHT 22d COMMON RE TURN CUNSTANT SUPPLY IHI TRAFFIC LIGHT 22a y 1967 D. c. GAZIS ETAL 3 3,323,106

TRAFFI C I NTERSECTION Filed April 29, 1964 l0 Sheets-Sheet 5 FIG. 5

v I 1: 111 I1 NORTH F SOUTH EAST F WEST TRAFFIC LIGHT 22 a y 1967 D. c. GAZIS ETAL 3,323,106

TRAFFIC INTERSECTION Filed April 29, 1964 l0 Sheets-Sheet 6 FIG.6

I JI III 13C 5) EAST TRAFFIC LIGHT 22b y 1967 D. c. GAZIS ETAL 3,323,106

TRAFFIC INTERSECTION Filed April 29, 1964 l0 Sheets-Sheet 7 I 6) NORTH f soumg r- WEST TRAFFIC LIGHT 22c y 30, 1967 D. c. GAZIS ETAL 3,323,106

TRAFFIC INTERSECTION Filed April 29, 1964 l0 Sheets-Sheet 8 FIG.8

I IE III ISZI NORTH soum EAST

WEST

TRAFFIC LIGHT 22d y 1967 D. c. GAZIS ETAL 3,323,106

TRAFFIC INTERSECTION Filed April 29, 1964 H 10 Sheets-Sheet 9 FIG.9

NORTH SOUTH TRAFFIC LIGHT 22e United States Patent 3,323,106 TRAFFIC INTERSECTKON Denos C. Gmis, Miliwood, N.Y., and Reut'rey B. Potts,

Erlndale, South Australia, Austraiia, assignors to International Business Machines Corporation, New York,

N.Y., a corporation of New York Filed Apr. 29, 1964, Ser. No. 363,354 3 Claims. (Cl. 340-40) This invention relates to methods and means for controlling traffic, and more particularly to trafiic intersections and control of tratfic therethrough.

One reason for the congestion on the roadways in cities and in rural areas is the buildup of traific at oversaturated intersections. Oversaturation occurs whenever a stream of traffic approaching a trafiic light becomes heavier than that which can be accommodated by the corresponding green portion of the traific light. Various well-known solutions have been employed to relieve the oversaturated condition. For example, overpasses have been constructed which permit one stream of traffic to pass over the top of the other stream of traflic, thereby permitting two continuous streams of trafiic to cross one another without delay. One apparent disadvantage of the overpass is the cost of construction, especially in cities where buildings and other structures would hamper the constructon of an overpass.

Still another solution to the problem of the oversaturated intersection is the familiar traffic circle. Normally the circle is made sufficiently wide to accommodate at least two lanes of oneway traffic so that the vehicles entering the circle in the right hand lane do not slow down the vehicles already on the circle in the left hand lane. Frequently, the vehicle in the left hand lane must cross over the right hand lane in order to leave the trafiic circle. This crossover, or weaving, is done in an unsupervised manner and safety is made to depend upon the skill and judgment of the individual drivers. Also, during periods of extreme congestion weaving toward various exits causes the traflic circle to lock-up blocking all movement of traffic.

Another problem associated with the trafiic circle is that all traffic is deflected around the circle including those vehicles which intend to proceed straight ahead without changing course or direction.

It is an object of the present invention to provide an improved traflic intersection.

It is another object of the present invention to provide an improved method of guiding streams of tratlic through an intersection.

It is a further object of the present invention to provide improved apparatus for synchronizing and controlling the flow of trafiic through an intersection.

Still another object of the present invention is to provide methods and means for permitting streams of trafi'ic to pass through an intersection without appreciable delay or high cost of installation of the intersection.

It is a further object of the present invention to provide methods and means for permitting streams of trafiic to flow through an intersection without requiring vehicles to cross over, or weave between lanes.

These and other objects of the present invention are accomplished by providing a novel intersection complex including a number of main roads leading to a central intersection, and a peripheral road surrounding the central intersection and crossing the main roads forming a number of exterior intersections, Traffic lights at the ex terior intersections divide the incoming traiiic into first and second platoons. The first platoons are directed onto the main roads leading to the central intersection. By proper timing of these traffic lights the first platoons arrive at the central intersection at alternate times thereby permitting continuous flow through the central intersection without delay.

The trafiic lights at the exterior intersections deflect the second platoons onto the peripheral road in a common one-way direction. Once again the tramc lights are synchronized and timed so that the second platoons arrive at exterior intersections at alternate times with the first platoons which have passed through the central intersection thereby permitting uninterrupted flow through the exterior intersections.

The first and second platoons originating from the same stream of traflic entering the complex are reunited at the exterior intersectons after the first platoons have traveled through the central intersection and the second platoons have traveled around the central intersection on the peripheral road. In this manner a larger number of vehicles are passed through the complex than that which can be accommodated by the central intersection.

This trafiic intersection complex can be constructed using existing city streets. Any four rectangular blocks can be employed with the central intersection located at the center and the peripheral roadway surrounding the outside of the four blocks. No modification or other structural changes need be made to the roads.

A further feature of the present invention is the absence of any crossover or weaving between lanes, thereby improving the safety of the system.

The foregoing and other objects, features and advantages of the present invention will be apparent from the following more particular description of preferred embodiments of the invention, as illustrated in the accompanying drawings.

In the drawings:

FIG. 1 is a schematic diagram illustrating an intersection complex constructed in accordance with the present invention;

FIG. 2 is an electrical schematic illustrating the control circuit shown in FIG. 1 and the connections to one of the traffic lights shown in FIG. 1;

FIGS. 3 and 4 illustrate the connections to four traffic lights shown in FIG. 1;

FIGS. 5 through 9 are waveform diagrams illustrating the signals applied to the five trafiic lights in FIGS. 2 through 4; and

FIG. 10 is a diagram illustrating another embodiment of the present invention which is an expanded version of the embodiment shown in FIG. 1 for accommodating a larger number of roads.

FIG. 1 illustrates an intersection complex including four main roads 11-14 leading to a central intersection 16a. A peripheral roadway 13 including segments fizz-18d surrounds the central intersection 16a and crosses the main roads 1144 at four intersections lob-e.

The peripheral road 18 surrounds four square blocks 2@ad with the intersection 16a located at the center. The top of the intersection complex shown in FIG. 1 is designated N (north), the bottom S (south), the left W (west), and the right side of the complex is designated E (east).

Located at the intersection 16a-e are traflic lights 22ae, respectively. The traific lights are 22 are operated by a control circuit 24 which synchronizes the operation in a manner to be described in detail with respect to FIG. 2.

In order to illustrate the general operation of the intersection complex shown in FIG. 1 the path of two streams of traffic entering from the north and west are described. In the illustrated embodiment the streams of traflic emerge from the complex in the same direction.

The stream of traific entering on the north is broken into two platoons 26a and 26b. The platoon of traffic may include a number of vehicles determined by the distance between intersections 1511-6 and the speed of the vehicles.

Platoon 26a is permitted to pass through intersection 16:: under control of traflic light 22c. Other vehicles in the stream of traffic entering the complex on the north side are deflected onto road 18a forming platoon 26b. After a complete traflic light cycle to be described in detain with reference to FIGS. -9 another platoon 26a is permitted to pass through intersection 162. In this manner the forming of platoons 26a and 26b is repeated over and over again, once in every light cycle.

The stream of traffic entering the complex at the west side is divided into two platoons 28a and 28b. Platoon 28a proceeds straight ahead, while platoon 28b is de flected to the right. The timing of traffic lights 22!) and 22:; is staggered so that platoon 26a arrives at intersection 16a and passes therethrough before platoon 28a arrives at intersection 16a. In this manner platoons 26a and 28a are interleaved at intersection 16a permitting a free flow of traffic without delay.

In a like manner the timing of traffic lights 22b and 22e is arranged so that platoon 26b travels through peripheral roadway 18a and arrives in time to cross at intersection 16b after platoons 28a and 28b have passed through and prior to the formation of another set of platoons 28a and 28b. Therefore platoon 26b is permitted to pass through intersection 16b without delay and continues on to intersection 160.

At intersection 160 the platoons 26b and 2812 are guided by traffic light 22c. Platoon 28b is permitted to pass through intersection 16c continuing on peripheral road 18c. Platoon 26b is deflected from peripheral road 18b to main road 12 in a direction away from central intersection 16a. At this time platoon 26b is reunited with platoon 2611 after platoon 26a has passed through central intersection 16a and platoon 26b has passed around intersection 16a on peripheral road 18a and 18b.

The traflic entering the complex on the south and east side is controlled by traflic lights 22c and 22d in the same manner as the traflic lights on the opposite side of the complex. Since the complex is symmetrical the operation of the platoons formed at intersections 16c and 16d is exactly the same as that described at intersections 16c and 16b respectively. For example when platoon 26a arrives at intersection 16a a similar platoon formed at intersection 160 also arrives at intersection 16a. Traffic light 22a permits the southbound platoon and northbound platoon to pass through intersection 16a at the same time and prior to the arrival of the westbound platoon and eastbound platoon formed at intersection 16b and 16d, respectively.

Detailed Description The details of the control circuit 24 are shown in FIG. 2. The traffic lights 22 are supplied with signals from control circuit 24 which operate the red, amber and green signal lights mounted on four sides of the traffic lights 22. A power supply 32 provides the current for illuminating the traffic lights 22. A battery 34 operates a group of relays R-I through R-IV and R-I through RIV under control of a pair of switches 52 and 54.

Battery 34 provides current to wiper arms 52a and 54a which are connected to a common shaft 55 and rotate in a clockwise direction at constant speed.

As shown in FIG. 2 the wiper arm 52a supplies current to a segment S-II connected via a line 58 to relay R-II. Current flowing from battery 34 flows through wiper arm 52a, segment S-II, line 53 to an operating coil 42a which pulls a contact 42b closed. The closing of contact 42]) causes power supply 32 to provide current on lines 60 and 62.

In a like manner wiper arm 52a passes over segment 8-H and engages a segment S-III. Relay R-III is operated causing power supply 32 to provide a signal on a pair of lines 64 and 66. Other segments of switch 52, designated 8-1 and SIV, are connected to relays R-I and R-IV.

When wiper arm 52a turns a full circle about switch 52 one cycle of operation is completed during which relays R-I through RIV are closed and opened in a sequential manner. In a like manner relays RI through R-IV are closed and opened in a sequential manner. However the interval of time during which the latter relays are closed is small as compared to the quarter cycle intervals of operation of relays R-I through RIV. This is due to the smaller size of the sectors on switch 54 designated S-I through S-IV For example, sector S-I is only about one-tenth'as large as the sector SII. Sector SI is located so that it makes contact with wiper arm 54a just prior to the time when wiper arm 52a engages segment SII. Located in this manner segment S-I closes the contact of relay R-I during the last portion of the interval when the contact of relay R-l is closed.

Also shown in FIG. 2 are the details of traffic light 22a which include four faces designated with N (north), W (west), S (south) and E (east). When faces N and E are swung into place and traffic light 22a is positioned as shown in FIG. 1, traffic approaching intersection 16a from the north observes the face designated N. Likewise traflic approaching from the west, south and east observes faces W, S and B, respectively.

Each face of traffic light 22a includes a red, amber and green signal light designated R, A and G. The vertical arrow adjacent to the green lights directs approaching traffic to proceed straight through the intersection 16a. Other green signal lights in FIGS. 3 and 4 include a horizontal arrow pointing to the right directing the approaching vehicles to turn right at the associated intersections 22b-22e.

The signal lights on traffic light 22a are connected to one or more of the contacts of relays RI through R-IV and RI through R-IV The red and green signal lights are connected to relays R- I through R-IV and the amber signal lights are connected to relays R-I through RIV All of the signal lights are connected to a common return line 68 which is connected to one side of power supply 32.

For example, a pair of red signal lights 60a and 60b are connected to relays RI and R-II via a line 60. Therefore vehicles approaching intersection 16a in FIG. 1 from the north and south are stopped during stages I and II of the control cycle. At the same time a pair of green signal lights 60c and 60d also connected to line 6% are illuminated permitting east-west flow of traffic through intersection 16a.

During stages II and IV the red and green lights on the four faces of trafiic light 22 are reversed in response to the signal on line 66. In between changes from green to red, the amber signal light on the associated face of traffic light 22a is illuminated for a brief moment to provide a caution or warning signal to the approaching vehicles. The amber signal lights are illuminated in response to the operation of relays RII and RIV which provide signals at the end of stages II and IV. The connections between the amber lights and relays R-II and RIV are shown in FIG. 2. The unused terminals from the control circuit 24 in FIG. 2 are utilized in FIGS. 3 and 4.

In order to summarize the operation of triflic light 22 shown in detail in FIG. 2 a set of waveforms is provided in FIG. 5. The four stages of the operating cycle are designated with I through IV at the top. The upper three waveforms represent the signal applied to the lights on the north face of traffic light 22a. When the waveform is in the upper level the associated signal light is illuminated, while the lower level of the waveform indicates that the light is not illuminated. During the first and second stages the red lights on the north and south faces of traflic light 22 are illuminated while the green lights on the east and west faces of traffic light 22a are illuminated as described above. The short illumination of the amber lights is represented by the narrow pulse-like waveforms.

As can be seen in FIG. the red and green lights are alternately turned on and off thereby interleaving trafiic at intersection 16a. Since the four stages of operation are equal in duration the full capacity of intersection 16a is divided between the approaching traffic on a 50-50 basis. That is trafiic approaching from the north and south share the green light portion of the cycle equally with the traffic approaching from the west and east.

FIG. 3 illustrates the connections between control circuit 24 and trafiic lights 2% and 220. The outputs from control circuit 24 are designated with one or more of the numbers I, II, III and IV indicating the stage or stages during which power is supplied to the associated terminal. In addition the common return terminal connected to line 68 and a constant supply terminal are designated as such. The constant supply terminal is connected to the red lights on the south and east faces of traffic lights 22b and 22c respectively. Since peripheral road 18 shown in FIG. 1 carries only one-way trafiic no further signal lights are required on these faces. Some of the faces of the traflic lights shown in FIG. 3 includes a green signal light having an arrow pointing to the right. When illuminated these signals direct the approaching traffic to make a right turn. For example the green light with an arrow to the right on the north face of traffic light 22b directs trafiic approaching intersection 16b on peripheral road 18:: to turn right onto main road 11 in a direction away from central intersection 16a.

The green light with the arrow to the right on the west face of traffic light 22b directs traffic approaching intersection 1612 from the west to turn right on peripheral road 18b thereby forming platoon 28b.

FIG. 4 shows the connections between the traffic lights 22:! and 223 and control circuit 24. The operation of traffic lights 22b-e is summarized in the waveform diagrams shown in FIGS. 69.

In order to illustrate the operation of trafiic lights 22b-e the formation of platoons 26a and 26b at intersection 162 is described. A summary of the operation of trafiic light 22a is shown in FIG. 9. During stage I and II trafiic approaching from the north passes straight through intersection 16c. During this time a waveform 72 indicates that a green light 7211 is illuminated. During stage III a green light 7401 is illuminated as indicated by a waveform 74. Waveform 74 is at the upper level during only a single stage or 25% of the full cycle. Therefore the platoon 26b shown in FIG. 1 is only /2 the size of platoon 26a formed during stages I and II.

Platoon 26a continues to travel down main road 14 arriving at intersection 16a at the beginning of stage III. Referring to FIG. 5 it may be seen that the green light on the north face of traffic light 22a is illuminated during stages III and IV permitting platoon 26a to pass through. The time interval for each stage is chosen with regard to the distance between intersection 16c and 16a as well as the speed of the vehicles so that minimum delay is encountered.

Platoon 26b formed during stage III travels along peripheral road 18a and arrives at intersection 16b at the beginning of stage I. Referring to FIG. 6 the north face of trafiic light 2212 provides an illuminated green light with an arrow straight ahead permitting platoon 26b to pass through. Since platoon 221) must travel a greater distance during the time interval of two stages than platoon 26a travels during the same interval, the speed limit should be raised or other conditions should be provided for balancing the difference in distance traveled by platoons 26a and 26b.

Platoon 26b continues its travel past intersection 16b on peripheral road 18b arriving at intersection 16c at the beginning of stage III. Referring to FIG. 7, the west face of traffic light 22c provides an illuminated green light with an arrow to the right during stage III. Therefore xi" platoon 26b is deflected from peripheral road 13b onto main road 12 in a direction away from central intersection 16a. Platoon 26b merges in behind platoon 26a which passes through intersection during stages I and III.

Traffic light 220 operates in the same manner as traffic light 226 with opposite faces exchanged. That is, the south face of traffic light 220 operate the same as the north face of traflic light 22e. Trafilc lights 22b and 22a are similar in operation to trafiic light 226 with two differences.

The first difference is that traffic lights 22b and 22c are delayed two stages behind that of trafiic light 22c with regard to the platoons directed into the main roads 11 and 13. Platoon 28a shown in FIG. 1 is formed during stages III and IV while platoon 26a is formed during stages I and II. This may be seen by referring to FIG. 6 where a waveform 7 6 indicates that the traflic moving west on main road 11 passes through intersection 16b during stages III and IV. By delaying the formation of platoon 28a two stages with respect to the formation of platoon 26a, these platoons arrive at alternate times at intersection 16a.

The second difference in the operation of intersections 22b and 22:! from intersection 22c occurs in the formation of platoon 28b. Platoon 28b is formed in stage II as illustrated by a waveform 78 shown in FIG. 6. The formation of platoon 28b is prior to the formation of platoon 28a as opposed to platoon 26b which is formed after platoon 26a. This difference is necessary in order to allow platoon 26b to pass through intersection 1612 during stage I providing uninterrupted flow of traffic.

In summary a traffic intersection complex is shown in FIG. 1 having a central intersection 16a surrounded by a peripheral road 18. A portion of the excess traffic over that which can be handled by intersection 16a is deflected around the peripheral road 18. A control circuit 24 provides synchronization and control over traffic lights ZZa-e so that uninterrupted flow of traffic is achieved.

Expanded Intersection FIG. 10 shows an expanded version. of the intersection complex shown in FIG. 1. Like designations are given to those roads in FIG. 10 which are the same as the roads in FIG. 1. Additional main roads l4 and 12' are added in FIG. 10 along with an extension 12% and 18d to the peripheral road 18. An additional central intersection 16a is formed.

The operation of the complex in FIG. 10 is similar to that in FIG. 1. For example trafiic entering the complex in FIG. 10 from the south at intersection 160 is divided into two platoons, one traveling straight through on main road 12 and the second platoon being deflected to the right onto peripheral road Mic. The platoon deflected onto peripheral road 18c follows a path through intersection 160, main road 12, intersections 16a and 16e peripheral road 18d reuniting with the: platoon traveling north on main roads l2 and 14 at intersection 16c.

Tr-aific approaching the complex from the south at intersection 160' is divided into two platoons. The first platoon proceeds straight through on main road 12 and the second platoon is deflected onto road These two platoons originating from the same stream of traflic are reunited at intersection 162 after the first platoon has traveled through intersection 16a and the second platoon has traveled through intersection 16d.

The operation cycle for the traflic complex shown in FIG. 10 is divided into six stages instead of four as in FIG. 1. The expanded number of stages is necessary in order to accommodate the complicated routing of traflic especially through intersections 16c and 162'.

While the intersection complex shown in FIG. 1 is able to increase the flow of traffic by 50% over the capacity of intersection 16a, the complex shown in FIG. 10 is capable of increasing the flow of traffic 33 /s% over the capacity of central intersection 16a and 16a. The size of the platoons deflected around the peripheral loops in FIG. 10

is /3 the size of the platoons permitted to proceed straight through the complex, while platoons 26b and 28b described in FIG. 1 are /2 the size of platoons 26a and 28a.

Further expansion of the complex over that shown in FIG. can be accomplished by adding additional main roads. Each time the intersection complex is expanded the number of stages in the operating cycle is also increased. The number of stages is determined by the number of intersecting streams of tratfic. For example, in FIG. 1, there are two streams of trafiic approaching the complex from the north and west. The streams of tratfic approaching in the opposite direction from the south and east need not be considered since they can be accommodated without effecting the number of stages. The actual number of stages is given by the formula 2N where N is the number of intersecting streams of traffic. In the case of FIG. 1, N :2. Therefore there are four stages in the operating cycle.

In the case of FIG. 10, N :3. Therefore six stages are required. Each additional stream of trafiic added to the complex creates the need for two additional stages in the operating cycle.

The amount of increase of traffic handled by the intersection complex over that which can be handled by the central intersection, or intersections, is given by the ratio l/N, Where N is the number of streams of traffic as defined above. In the case of FIG. 1, N =2 indicating an increase of 50%. In the case of the intersection complex in FIG. 10, N=3 indicating an increase of 33% The embodiments of the present invention shown in FIGS. 1 and 10 employ the roadways surrounding square blocks in order to use existing streets. However it is apparent that the shape of the peripheral roadway 18 could be altered to fit existing streets other than rectangular shapes. For example an improvement could be made by having a straight path between intersections 16c and 16b in FIG. 1, thereby decreasing the distance traveled by platoon 26b and providing for a more uniform speed.

In addition to the advantage of employing exisiting roads, the present invention does not require vehicles to cross over or weave between lanes as can be seen by examining FIGS. 1 and 10.

Although the embodiment shown in FIG. 1 employs a 5050 split in the service of traffic approaching central intersection 16a other proportions can be used if the traffic demands are unbalanced. Also, the traffic light 22a can be eliminated entirely if the vehicles maintain the same speed and platoon formation.

The embodiment shown in FIG. 1 does not permit traffic approaching the intersection complex to leave the complex at other than the prescribed exit at the opposite side of the complex. Right turns can be effected without interference with the operation. For example vehicles approaching the complex on the north becoming part of platoon 2611 could leave the complex at intersection 16b by making a right turn without causing delays. However modifications of the control of trafiic lights 22 would be 8 necessary in order to permit right or left turns at central intersection 16a or to permit vehicles to continue straight through intersections 16b-16e when right turns are indicated to be proper in the embodiment as shown in FIG. 1.

While the invention has been. particularly shown and described with reference to preferred embodiments thereof, it will 'be understood by those skilled in the art that the foregoing and other changes in form and detail may be made therein without departing from the spirit and scope of the invention.

What is claimed is:

1. The method of guiding streams of traffic through a complex of roads including two main roads crossing at a central intersection and a peripheral road surrounding said central intersection and crossing said main roads forming four exterior intersections each said main road carrying a stream of traffic to said complex, said method comprising the steps of:

dividing each of said streams of traffic entering said complex at said exterior intersections into first and second platoons;

directing all of said first platoons into said main roads with alternately timed arrivals at said central intersection permitting said first platoons to pass through said central intersection without delay;

deflecting all of said second platoons onto said peripheral road in a common direction about said central intersection, the deflection being timed to permit alternate arrival of said first and second platoons at said exterior intersections opposite their point of division; and

uniting the first and second platoons originating from the same stream of traffic entering said complex along one of said main roads after said first platoons have passed through said central intersection and said second platoons have passed through said exterior intersections.

2. The method as defined in claim 1 including dividing said streams of traffic so that said first platoons fill the capacity of said central intersection without causing overlap in the time of arrival of said first platoons at said central intersection.

3. A method as defined in claim 1 including dividing said streams of traffic so that each of said first platoons contain no more than 50% of the capacity of said central intersection and said second platoons contain no more than 25% of the capacity of said central intersection.

References Cited UNITED STATES PATENTS 2,133,157 10/l938 Turner 340-40 2,980,887 4/1961 Soderberg 340-40 NEIL C. READ, Primary Examiner. THOMAS B. I-IABECKER, Examiner. 

1. THE METHOD OF GUIDING STREAMS OF TRAFFIC THROUGH A COMPLEX OF ROADS INCLUDING TWO MAIN ROADS CROSSING AT A CENTRAL INTERSECTION AND A PERIPHERAL ROAD SURROUNDING SAID CENTRAL INTERSECTION AND CROSSING SAID MAIN ROADS FORMING FOUR EXTERIOR INTERSECTIONS EACH SAID MAIN ROAD CARRYING A STREAM OF TRAFFIC TO SAID COMPLEX, SAID METHOD COMPRISING THE STEPS OF: DIVIDING EACH OF SAID STREAMS OF TRAFFIC ENTERING SAID COMPLEX AT SAID EXTERIOR INTERSECTIONS INTO FIRST AND SECOND PLATOONS; DIRECTING ALL OF SAID FIRST PLATOONS INTO SAID MAIN ROADS WITH ALTERNATELY TIMED ARRIVALS AT SAID CENTRAL INTERSECTION PERMITTING SAID FIRST PLATOONS TO PASS THROUGH SAID CENTRAL INTERSECTION WITHOUT DELAY; DEFLECTING ALL OF SAID SECOND PLATOONS ONTO SAID PERIPHERAL ROAD IN A COMMON DIRECTION ABOUT SAID CENTRAL INTERSECTION, THE DEFLECTION BEING TIMED TO PERMIT ALTERNATE ARRIVAL OF SAID FIRST AND SECOND PLATOONS AT SAID EXTERIOR INTERSECTIONS OPPOSITE THEIR POINT OF DIVISION; AND UNITING THE FIRST AND SECOND PLATOONS ORIGINATING FROM THE SAME STREAM OF TRAFFIC ENTERING SAID COMPLEX ALONG ONE OF SAID MAIN ROADS AFTER SAID FIRST PLATOONS HAVE PASSED THROUGH SAID CENTRAL INTERSECTION AND SAID SECOND PLATOONS HAVE PASSED THROUGH SAID EXTERIOR INTERSECTIONS. 